Locking mechanism for doors



y 1934. D. F. SMITH ET AL ,9

LOCKING MECHANISM FOR DOORS Filed April 22, 1955 INVENTORS I BYW I M ATTORNEY Patented July 10, 1934 UNITED STATES PATENT DFFICE Daniel F. Smith, New York, N. Y., and William F. Purcell, Hoboken, N. J.

Application April 22, 1933, Serial No. 667,338

3 Claims.

This invention relates to locking mechanisms for doors, and particularly to mechanisms which permit the occupant of a house or room to see who seeks admission before unlocking the door.

We are aware that devices for this purpose are in use, as for example, a chain which permits a door to be partly opened but which has to be unhooked to allow the door to be fully opened, or an opening in the door, through which the person within may look before unlocking the door. These devices, however, do not fully meet the requirements, as the occupant is very likely to forget to hook the chain or to look through the opening before unlocking the door. The object of our invention is to provide a mechanism which the occupant cannot forget to use.

The invention consists in providing a locking mechanism which cannot be unlocked, from within, until the operator has opened a shutter which normally covers an opening, provided for investigation, and in certain details of construction to accomplish this object as illustrated and described herein.

In the accompanying drawing:-

Figure l is an elevation of a door as viewed from within and showing it locked.

Figure 2 is a similar view showing the door unlocked and ready to be opened.

Referring to the drawing in detail, 1 indicates the door frame, 2 the door saddle and 3 the door, hung on hinges 4. A lock 5 having a latch-bolt 6, which engages the latch-plate 7, when the door is closed, is secured to the door in the usual manner. This lock may be of conventional construction, of the type in which the latch-bolt is withdrawn from the latch-plate by turning the knob 8 on the inside of the door, or by means of a key from the outside, except that a secondary latch 9 is provided which engages a projection 10, on the knob stem, and prevents the knob being turned until this latch is disengaged, as shown in Fig. 2.

The numeral 11 indicates an opening in the door which is normally covered by a shutter 12, provided with a knob 13 for the purpose of moving it. This shutter is pivotally attached to the door at 14 and a rod, or other connecting means 15 is pivotally attached to the shutter at 16 and to the secondary latch of the look at 1'7 so that when the shutter is swung upwardly, as shown in Fig. 2, the latch 9 will be raised out of engagement with the projection 10 and the knob 8 can then be turned to open the door.

It is thought that the operation of the device will be obvious. Assuming that the occupant of a house or apartment is summoned to open the door and forgets to investigate, he will find that he cannot unlock the door until he has moved the shutter 12 so as to expose the opening 11, as shown in Fig. 2, and will thereby be reminded to see who seeks admission.

For the purpose of illustration we have shown one form of the invention but do not limit ourselves to the precise construction shown, as modifications may be made to adapt the device to diiierent conditions without departing from the scope of the claims.

We claim as our invention:--

0 1. In a locking mechanism for a door, the combination of a shutter adapted to normally cover an opening, a lock having a latch-bolt adapted to engage a latch-plate to hold the door closed, a secondary latch capable of preventing withdrawal of said latch-bolt from said latch-plate and means operated by moving said shutter to disengage said secondary latch.

2. In a locking mechanism for a door, the combination of a shutter adapted to normally cover an opening, a lock adapted to hold the door closed, said lock having a rotatable member capable of withdrawing a latch-bolt, a secondary latch adapted to prevent said member being rotated and a member connecting said secondary latch to the shutter so that movement of the shutter will disengage said secondary latch from the rotatable member.

3. In a locking mechanism for a door, the combination of a shutter adapted to normally cover an opening in said door, a lock for said door, said lock having a rotatable member to permit opening of said door and means, controlled by said shutter, for rendering said member iii-operative until said shutter is moved to uncover said opening in the door.

DANIEL F. SMITH. WILLIAM F. PURCELL. 

